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R Pete
Its was the background info on the ebay site
, that I had spotted , the r820t running to
1.7 GHz ?
that has to worth a look ?
73 -G.
Sent: Sunday, April 07, 2013 3:57 PM
Subject: LF: Re: LF: Re: £10 Dongel-SDR Direct sample on 504 KHz -
S/N TEST
Hi Graham
Cozy Cave still cheaper?????? that's with all the UK Tax
(support UK!!!)
Your shopping basket contains 1
product
| Product |
Description |
Ref. |
Avail. |
Unit price |
Qty |
Total |
| Total products (incl. tax): |
£7.95 |
| Total shipping (incl. tax): |
£1.98 |
| Total (excl. tax): |
£9.93 |
| Total tax: |
£0.00 |
| Total (incl. tax) |
£9.93 |
73 es GL Pete M0FMT IO91UX
Looking at ebay , one seller has
the RTL2832U & R820T
dongle and indicates 25 to 1700 MHz range
, using the r820t in place of the
e4000 front end ..... Item number:
160896097557
This is 'handy as the
original chip set items are becoming difficult
to source and over priced !
Defiantly the green light
to hack the original for MF/HF and
buy the new for vhf/shf
73's Graham
Sent: Sunday, April 07, 2013 9:33 AM
Subject: LF: Re: £10 Dongel-SDR Direct sample on 504 KHz - S/N
TEST
Hi Graham,
Yes I have the slider set to (nearly) maximum on 2
and 70 J
With a direct compare (same antenna, same signal) the dongle is
definitely less sensitive than my 897, I suspect (but have not scientifically
determined) at least several s-points. I only tested NFM. Other dongle owners
here report the same so it is not an issue with my copy of the
dongle…
73’s Minto pa3bca
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Ceterum
censeo Carthaginem delendam esse
Sent: Sunday, April 07, 2013 02:00
Subject: Re: LF: Re: £10 Dongel-SDR Direct sample on 504 KHz - S/N
TEST
Ok...Minto,
- silly question , you have the gain slider
set max in the driver set-up panel ? Then agen , my
ft897 could be u/s !
I will shorten the min coax I have soldered
to the device , and see what happens on
VHF with the gen on Sunday
with the same levels , ive emailed
you a recording of ssb station on
4 meters , using the dongle and
indoor Ae
73 -G,.
Sent: Saturday, April 06, 2013 11:16 PM
Subject: LF: Re: £10 Dongel-SDR Direct sample on 504 KHz - S/N
TEST
Hi Graham,
So maybe I should order another (type) of RTL2832
dongle. The one I have certainly is wayyy less sensitive than my ft897 on 2
and 70. Probably the type of tuner is different.
Well for the direct
sampling test it is irrelevant. I will have to filter 472, but that is no
problem as I already have such a filter (ft817 will overload from AM@675 without the
filter).
I also have a 1.8 MHz higpass. And as you say, at EUR 10 for
a dongle there is not much to complain about. It is fascinating that it works
so well as it does.
73’s Minto pa3bca
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Ceterum
censeo Carthaginem delendam esse
Sent: Saturday, April 06, 2013 23:58
Subject: Re: LF: Re: £10 Dongel-SDR Direct sample on 504 KHz - S/N
TEST
Ok Minto
Yes this is the Q not Q or what ever
connection to the A/d
As to improvement's , ive no idea ! , but
you note the coupling C are
both removed , the gain from the mini-whip my
well be enough to 'tip the balance'
but s/n for data is more
important than 'peak signal level' so gain
(lots) may not be the holy grail , I did
copy nav text at 100% from the south of Uk ,
audio level was very low , but at a good
s/n.
[ Gary's point , yes could switch , but I have
the impression , more could be gained by
using the balanced feed as in the link
above , you can run 2 dongles in the
same pc as the usb location seems
to be part of the driver addressing
There is 'no' gain in the A/D , to
day , the racal ra6790 produced a S3
/ 4 cw copy from 0.1 uV , as can be
seen from the s-lab shot , but a low noise pre-amp
would solve the problem and with no
additional mixer , IMD should be much
reduced , night time HF was quite reasonable ,
left it on 14,103 with the 40ft
vertical, returned after dinner and had
missed Iceland with -8dB signal .. typical
!
The mixer in the dongle cannot
have much dynamic range , compared to one
designed for 'HF , eg the ra1769
first mixer is fed with 5 to 7 watts
of RF to ensure minimal transit times and
over 120 dB dynamic range , this could
be a contributing factor to any 'strange
patterns , which must be aggravated by
having two mixers in the rf path -
one may be 'good' but the e4000
may not be , where as the a/d seems
to be quite clean
You have the same item I have hacked for MF
, showing in the driver list as generic , the
other is the original ezeycap as per the first
posts ... When you say the vhf/uhf
is 'low' that's odd as I would say
this one (ezy) is as good as the
ft897d on 2/70 and on 4 meters , its better than
the spectrum trans V , using HDSDR
But the main thing is , it put's a
reasonable set-up in a very affordable
price , will be interesting to see the
performance ,D/S linked to the mini-whip , may be
the only way round the large carrier
problem will be filtering , or a
move to a better a/d , at least any
pre-amps and filters are transferable ,
should a better A/D be used at
a future data ?
73 -G.
Sent: Saturday, April 06, 2013 10:15 PM
Subject: LF: Re: £10 Dongel-SDR Direct sample on 504 KHz - S/N
TEST
I have been experimenting too with an RTL-SDR dongle
now for a few weeks. I currently use a transverter to listen to lf/mf/hf. This
transverter upshifts the spectrum with 100 MHz.
Although the RTL-DSR is
rather deaf when used on 2m or 70 cm (compared to my ham equipment) when used
for HF it is sensitive enough with a pa0rdt active antenna.
I can also use
it on 472. But there I have to use my 472 KHz narrow band filter to keep out
mf, especially Radio Mario @ 675 Khz. And although the dynamic range is not
stellar, as far as I can determine reception on 472 is very
comparable to my ft817..
Grahams pointer to the direct sampling option got
me interested. Time to let the nice people from dealextreme send me another on
for EUR 10 so I can ‘experiment’ with it.
First site is in Japanese, second in Croatian, but
Google (translate) is your friend.
It is very nice to get an instant overview of 2 MHz
of spectrum. I have been plagued by ever increasing QRM here, which forced me
to place a magnetic loop antenna in my backyard to get any reception at all.
QRM now is S9+10 dB form 100 KHz to nearly 50 MHz. I have not been able to
find out what causes this (not generated in my house). See attached screenshot
for a part of the spectrum around 80 meters. This wavy
pattern can be seen everywhere from nearly DC to 50 MHz, with some clean
area’s in between. Sometimes the QRM stops waving – straight lines for several
seconds and then the waving restarts.
I am very jealous of other hams showing waterfall
patters where everything between real signals is dark blue...
:-(
Anybody ANY idea what might cause this kind of QRM?
73’s Minto pa3bca
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Ceterum
censeo Carthaginem delendam esse
Sent: Saturday, April 06, 2013 19:55
Subject: Re: LF: £10 Dongel-SDR Direct sample on 504 KHz - S/N
TEST
Graham,
Maybe then....if the PCB was installed in a small
aluminium box the capacitor could be removed & a switch fitted to select
the original (VHF) arrangement or the HF/LF method. Possibly fit a pre-amp
also.
73, Gary - G4WGT.
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